The present invention relates generally to free acid measuring devices and methods and more specifically, it relates to a continuous-flow, monitoring system and method for the measurement of the free acid concentration in a process stream.
Aqueous reprocessing of spent nuclear reactor fuel involves the initial dissolution of fragmented fuel bundles in strong acid, usually nitric acid. This solution is then clarified by filtration or centrifugation and made up to a desired acidity prior to extraction of the uranium and plutonium. During the dissolution stage, the acid concentration becomes unpredictably altered. The free acid concentration is crucial at this point, must be measured and adjusted to the proper acidity prior to extraction of uranium and plutonium. Excessively high acid concentration results in incomplete separation of fission products from the uranium and plutonium, and concentrations below the desired level result is losses of uranium and plutonium. The nature of the solution with respect to radioactivity and inhomogeneity make sampling and free acid determination by conventional methods difficult and time consuming. It has generally been the practice to randomly sample the process stream and make acid determinations by direct titration. This requires considerable hold-up time and prevents the immediate return of the sample to the process stream. Further, handling of the samples must be done in a hot cell due to the high radiation levels present in the early stages of fuel reprocessing streams. Thus, there is a need for a method and a system for an accurate determination of free acid that is compatible with a continuous operation in a hostile environment.
Therefore, it is an object of this invention to provide a continuous-flow method for measuring the free acid in a process stream.
Another object of this invention is to provide a system for in-line monitoring of free acid in the process stream.
Other objects, advantages and novel features of the invention will become apparent to those skilled in the art upon examination of the following detailed description of the invention taken in conjunction with the accompanying drawings.